Continuous casting starter bar

ABSTRACT

In a dummy bar having a head for temporarily plugging a continuous casting mold, the cross-sectional dimensions of links of a chain, which is removably attached to the dummy bar head, are adjustable so that the ends and sides of the links will be supported and guided by the rollers of the roller apron of the casting apparatus when the cross-sectional shape and dimensions of the roller apron are changed to correspond to the shape and dimensions of beam blank and slab molds of different sizes. The links have the cross-sectional shape of the smallest beam blank and are in two halves separable at a break laterally across the web portion and held together by removable tie rods. Inserts are mounted between the halves to adjust the width; the thickness of the inserts determines the adjustment for the thickness of the web of a beam blank. For slabs the rollers of the roller apron engage the flanges of the beam blank shape of the web. A storage rack for the dummy bar chain is adapted to support and and to separate the halves of all the links at once for inserting, removing or exchanging the inserts.

United States Patent lnventors Georg Bollig Buderich, Germany; Eric T. Vogel, Elmhurst, N.Y. Appl. No. 805,628 Filed Mar. 10, 1969 Patented Sept. 28, 1971 Assignee Concast Incorporated New York, N.Y.

CONTINUOUS CASTING STARTER BAR 11 Claims, 14 Drawing Figs.

m1 momma Primary ExaminerR. Spencer Annear Attorney-Sandoe, Hopgood & Calimafde ABSTRACT: In a dummy bar having a head for temporarily plugging a continuous casting mold, the cross-sectional dimensions of links of a chain, which is removably attached to the dummy bar head, are adjustable so that the ends and sides of the links will be supported and guided by the rollers of the roller apron of the casting apparatus when the cross-sectional shape and dimensions of the roller apron are changed to correspond to the shape and dimensions of beam blank and slab molds of different sizes. The links have the cross-sectional shape of the smallest beam blank and are in two halves separable at a break laterally across the web portion and held together by removable tie rods. inserts are mounted between the halves to adjust the width; the thickness of the inserts determines the adjustment for the thickness of the web of a beam blank. For slabs the rollers of the roller apron engage the flanges of the beam blank shape of the web. A storage rack for the dummy bar chain is adapted to support and and to separate the halves of all the links at once for inserting, removing or exchanging the inserts.

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sum 1 OF 5 tom 1 Nu Wnl QQ E 9 mOE NOE ERIC T. VOGEL ATTORNEYS PATENT-EU saves lsn SHED 2 OF 5 IN VENT )RS scone a. some v ERIC 1. VOGEL IITOR NEYS PATENTEDserzamn 3,608,519

sum 3 or 5 INVENTORS GEORG B. BOLLIG ERIC 1. VOGEL BY I fwd/M ATTORNEYS PATENIEU SEP28 Ian sum 8 OF INVENTORS GEORG B. BOLLIG ERIC T. VOGEL ATTORNEYS PATENTED SEF28 197p sum 5 or 5 INVENTORS GEORG B. BOLLIG DOE ERIC 1. VOGEL ATTORNEYS CONTINUOUS CASTING STARTER BAR FIELD OF INVENTION This invention relates to the continuous casting of metal, particularly steel, and to a dummy bar chain which is adjustable for use in the casting of beam blanks and slabs of different sizes.

In continuous casting, open ended molds are employed to form a strand from molten metal poured therein. In order to start the continuous casting process, a dummy bar having a dummy bar head is inserted into the apparatus to block the bottom of the mold and prevent molten metal initially poured into the mold from escaping until it has solidified to form a strand. The dummy bar head is so formed that the end of the strand becomes secured thereto so that the dummy bar may be utilized to pull the strand from the mold until the strand reaches driven extractor rolls in the casting apparatus. After the strand has been gripped by the extractor rolls, the dummy bar is separated from the dummy bar head and stored out of the way of the issuing strand.

PRIOR ART When the size of the shape of the casting mold is changed, the dummy bar head has to be changed accordingly. The cross-sectional area between the rolls of the roller apron, or the cross-sectional area of the chute, if a chute is being used instead of a roller apron, has also to be changed accordingly in order to give proper support to the issuing strand. Apparatus to perform these functions is known to the art. Different dummy bars corresponding to the different size or shape of the casting mold have been employed in the past, but this creates extra costs for all the different dummy bars and also represents a storage problem. It has been proposed to use only one dummy bar, which has the smallest dimension of all different sizes of castings, and to attach larger dummy bar heads for larger castings. However, it is very difficult and time consuming, and requires additional, expensive equipment to guide such a dummy bar having a larger head, when the dummy bar is moved upward in the apron, and to introduce the head into the mold before the beginning of the casting.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a dummy bar which can be adjusted for the casting of beam blanks (dog bone shapes) of different sizes, and also for the casting of slabs of different sizes, while the interchangeable adjustment members of the dummy bar provide means for the accurate guidance of the dummy bar and the attached head in the roller apron or chute and for the accurate introduction of the head into the mold.

Another object is to provide a storage rack for a dummy bar incorporating means for quickly separating the components of the dummy bar along its entire length at one time. for inserting, removing or exchanging the adjustment members, for reassembling the components and for guiding the dummy bar when it is reintroduced into. the roller apron.

THE DRAWINGS Further objects, advantages and features of this invention will be apparent in the following description of illustrative embodiments shown in the accompanying drawings wherein:

FIG. 1 is a vertical cross-sectional view of a continuous casting machine showing a dummy bar head and chain of this invention used therewith;

FIG. 2 is a top view of a beam blank mold;

FIG. 3 is a top plan view of a slab mold;

FIG. 4 is a cross-sectional view of a link of the dummy bar chain at its smallest size of adjustment and is taken on line 4- 4 of FIG. 6;

FIG. 5 is a view similar to the view of FIG. 4 but showing the link with a spacer inserted for enlarging it and is taken on the line 55 of FIG. 6;

LII

FIG. 6 is a plan view, partly in section, of a representative portion of an assembled dummy bar chain;

FIG. 7 is a side elevation of the portion of an assembled dummy bar chain shown in FIG. 6;

FIG. 7a is a side elevation similar to FIG. 7, but showing spacers of a different size in the chain links;

FIG. 8 is a side elevation of the dummy bar head and transition members of the dummy bar chain;

FIG. 9 is a plan view, partly in section, of the dummy bar head and transition members shown in FIG. 8;

FIG. 10 is a radial section through the roller apron adapted for guiding a slab from a slab mold;

FIG. 11 is a plan view of the storage rack;

FIG. 12 is a section on the line 12-12 of FIG. 13; and

FIG. 13 is a top view of a representative portion of the dummy bar separation apparatus of the storage rack.

DETAILED DESCRIPTION Referring to the drawings, FIG. 1 shows a continuous casting machine in vertical section in which an open-ended mold 10 has a mold cavity 11 which has either the cross section of a beam blank 110 formed by beam blank mold in FIG. 2, or the cross section of a slab 11b formed by slab mold 10b in FIG. 3.

For the start of casting, a dummy bar 12 is moved up along a roller apron 13 by driven rolls 14 to plug the bottom of the mold cavity 11. The dummy bar 12 consists of a dummy bar head 15, transition members 16, and chain links 17. In the starting position, the head 15, which has approximately the same cross section as the mold cavity 11, plugs the mold cavity. One end of the head 15 has a protruding member 18 which will be surrounded by molten metal so as to become firmly attached to the strand which is formed by the solidifying metal in the mold cavity 11. Then the strand and the dummy bar 12 are withdrawn by the driven rolls l4 and move down a path defined by the roller apron 13.

When the smallest scheduled size of a beam blank Ila is being cast, the cross section of the chain links 17 have the same dimensions as said beam blank Ma. No transition members 16 are necessary in this case and the head 15 is attached directly to the first chain link 17.

FIG. 4 shows chain link 17 adapted for use when the smallest size beam blank 11a is being cast. It has two flanges 22 and a web 23, and is cut in two halves 24 and 25 bolted together by tie rod 26. The web 23 has guide surfaces 230 and is guided by the rollers 27 of the roller apron 13.

FIG. 5 shows the chain link 17 as enlarged when larger size beam blanks 11a are being cast. In this instance two halves 24 and 25 are moved apart with a spacer 28a placed between them and secured to a longer tie rod 26. A perfect alignment of spacer 28a with the left half 24 is effected by the protruding head 31 of a bolt 32, which fits into corresponding cavities in beam half 24 and spacer 28a. The right beam half 25 is aligned with the spacer 28a by the protruding head 33 of a bolt 34 which is bolted to spacer 28a. The length L of spacer 28a compensates for the desired larger width W of the beam blank Ila, so that the opposite flange faces 35 and 36 are accurately guided laterally by rollers 37 of roller apron 13.

If the thickness of the web 23 of the beam blank to be cast remains unchanged, the thickness T, of spacer 28a is thinner than web 23, and the rollers 27 guide web 23 as previously shown in FIG. 4. If, however, the thickness of the web of the desired larger beam blank has also been increased, an alternative spacer 28b is used, which has a correspondingly increased thickness T shown in dotted lines. As shown, the spacer 28b is thicker than web 23 and in this case the web portion of the link is guided by the rollers 27 bearing against the side surfaces 38 of spacer 28b.

FIG. 6 is a plan view, partly in section, of a dummy bar chain composed of the above-described dummy bar chain links 17. The beam blank halves 24 and 25, which together with the spacers 28a, represent one link 17 of the dummy bar chain, are coupled to the adjacent links 17 in a staggered manner by pivots 41. As noted above, for casting a beam blank 110 with a thicker web, a thicker spacer, e.g. spacer 28b, is used, but it will be understood, however, that for a particular size beam blank, the lengths L and thicknesses T of the spacers in the respective chain links 17 are the same for each link.

FIG. 7 shows the assembled dummy bar chain 17 of FIG. 6 in side elevation. As shown, the webs 23 of the links are each convex on one end and concave on the other, and successive links are arranged with the convex and concave ends of their respective webs in complementary relation to provide substantially continuous bearing surfaces for the rollers 27 as the links flex to follow the curvature of the roller apron 13. Each chain link 17 has a spacer 28a which has no guide functions in respect to rollers 27 and can therefore be shorter than the chain link 17 in which it is inserted (as well as being thinner than web 23).

FIG. 7a illustrates the use of the thicker spacers, 28b, which, as mentioned, are guided by rollers 27. To facilitate the guidance of spacers 28b by rollers 27, the spacers 28b, like the webs 23, are convex on one end and concave on the other so that adjacent ends of two adjacent spacers 28b interfit to provide a substantially continuous guide surface of the rollers 27, but with sufficient clearance between adjacent ends of each pair of spacers 28b to permit flexibility in the chain oflinks 17.

When adjacent links 17 are in straight alignment, the end faces 42 at the bottom of adjacent flanges 22 of adjacent links 17 bear on each other. One end face 43 at the top of the flange 22 of one link 17 is at an angle less than a right angle to the axis of its link and the adjacent end face 44 of the next link is at right angles to its axis. Thus, the dummy bar chain is adapted to be bent in one direction, from straight condition, to follow the curvature of the roller apron, but will not bend in the opposite direction from straight condition. In a preferred form, each upper end of the adjacent flanges 22 has a staggered arrangement of end faces 43 and 44, which are overlapping and provide mutual lateral support between two adjacent flanges 22.

FIG. 8 shows the dummy bar transition members 16 and the dummy bar head in side elevation. The transition members 16 have exactly the same general design features as the chain links 17 except that they are tapered from one end to the other; from the flange height h at the tail (right) end of the first transition member 16a, which is also the flange height of the chain link 17, the flange heights gradually increase along the successive lengths of the two adjacent transition members 160 and 16b up to a flange height H at the head end of transition member 16b. This height H matches the height of the dummy bar head 15.

It should be noted, that the web 23 and the spacers 28a or 28b, if spacers are used, always have the same centerline as the centerline of the increasing flange height, and the distance of the centerline from the bottom of the flange therefore increases from 11/2 at the beginning of transition member 16a to H/2 at the end of transition member 16b. Since all parts of the dummy bar 12, consisting of the chain links 17, the transition members 16 and the'head 15, are guided by rolls 27 which act on web 23 or spacers 280 or 28b, a perfect centering of the dummy bar 12 and a smooth introduction of the head 15 into the mold cavity 11 is accomplished.

The dummy bar head 15 consists of the link member 150 and the strand connection member 15b. The link member 15a is pivotally connected to transition member 16b in the same fashion in which the described links are connected, by a pivot 41. The strand connection member 15b carries the protruding members 18, which may be bolts, and which will be surrounded by solidifying metal in the mold cavity 11 so as to firmly connect the strand to the dummy bar at the start of the casting. Both members 1511 and 15b have webs 23 which are guided by rollers 27 as previously described.

In a preferred form, the members 150 and 15b are not equipped with spacers, but are manufactured to fit without adjustment for each required size, and are exchanged for each required change ofsize.

Referring back to FIG. 1, after the chain links 17 and the transition members 16 have passed through the driven rolls 14 they are guided on a storage rack 71 (indicated schematically) which is above a runout table (indicated schematically). The storage rack 71 is pivotally mounted to be swung down to intersect the runout table 85 at an angle-12, for exampleto receive the dummy bar chain of links 17 and transition members 16. After the strand connection member 15b and a short portion of the strand have passed through the rolls 14, the storage rack 71 is lifted up as indicated by the arrow. This separates the transition member 16b, and link member 15a which remains attached thereto, from the connection member 15b, which remains connected with the strand by the protruding members 18 which are embedded into the strand. Thus lifting up the storage rack 71 also lifts it out of the path of the strand along the runout table 85.

Referring to FIGS. 8 and 9 for adapting the parts to be thus disconnected by raising the storage rack 71, the members 1511 and 15b are connected by pivot 51, which has a round part 52 attached to member 15b. Another part 53 of pivot 51 is curved at two opposite sides and its top and bottom sides are flattened to permit passage of the rolls 27. This part 53 is received in a cavity 54 in the member 150. Cavity 54 has a diameter which is larger than the diameter of part 53 and the lower right part 56 of cavity 54 is flared outward. Thus, when the member 1511 is lifted by the storage rack 71, the part 53 slips out of the cavity 54, thereby disconnecting link member 15a from strand connection member 15b.

The above described dummy bar chain links 17 can also be used for the casting of slabs, which have a rectangular cross section 11b as shown in FIG. 3. FIG. 10 shows a representative chain link 17 guided by radial rollers 61 acting on flange ends 63 and lateral rollers 62 acting on flange faces 35 and 36. The rollers 61 and 62 also guide and confine the cast slab. The height h of the flange of chain link 17 corresponds to the height of the slab, and cannot be changed. The width W of chain link 17 corresponds to the width of the slab but can be adjusted as required by inserting spacers between the beam blank halves of chain link 17 in the manner previously described.

FIG. 11 shows a plan view of the storage rack 71 on which the dummy bar chain links 17, the transition members 16 and the link member 15a have been stored after they have passed the driven rolls 14. If no change in the cross section of the strand is required for a subsequent casting run, the assembled dummy bar 12 is ready for reuse by connecting link member 15a to a strand connection member 15b.

When the chain links 17 (and transition members 16) enter the storage rack 71 they are centered thereon by a guide 72, and the lower portions of the flanges of the links 17 and transition members 16 are received in cradles 73, which are spaced in staggered array at regular intervals on both sides of the centerline of the rack 71.

As shown in FIG. 12 and 13, the cradles 73 have approximately the same contours as those parts of links 17 which are received, and friction between the links and the cradles are reduced by rollers 74. Each cradle 73 is attached to a rod 75. Two adjacent rods 75 are attached to a toggle lever 76, which moves around pivot 77 to move the cradles laterally across the rack 71 simultaneously in opposite directions. The toggle lever 76 is in turn pivotally connected to rod 78, which is moved longitudinally by hydraulic cylinders 79.

The method of operation will best be understood by referring to FIGS. 4, 5, 11, 12 and 13. Ifa change in the cross section of the strand is desired, spacers 280 or 28b, or other spacers of larger or smaller size, are inserted between beam blank halves 24 and 25, or such spacers are removed or replaced, the tie rods 26 having been removed previously to free the beam blank halves 24 and 25, which remain supported in position by the cradles 73. Thereafter the cylinders 79 axially move rod 78, which in turn transmits the movement by means of the toggle levers 76 to the rods 75, causing one cradle 73 to move to the left, and the other cradle 73 to move to the right for an equal distance, thereby spreading apart the beam blank halves 24 and 25 to crate the necessary gap for removal, insertion or exchange of spacers 28a or 28b. it should be noted that the chain links 17 and the beam blank halves 24 and 25 are always supported by rollers 81; the eradles 73 merely transmit the separating movement and prevent the halves 24 and 25 from tilting. After the spacers 28a or 28b have been removed, inserted or replaced, the two halves 24 and 25 are moved in the opposite direction by a reversal of the above described operation, and the tie rods 26 are refastened to prepare the dummy bar chain links for operation. The above described procedure also applies to any transition members 16 which are used. The link member 15a, however, must be replaced manually as a separate operation. When the reassembled dummy bar 12 is reinserted from the storage rack 71 onto the runout table 85 and then back up into the roller apron 13, the guide 72 and the cradles 73 on the rack 71 insure that the dummy bar 1-2 stays in the centerline of the casting machine.

The embodiments of the invention shown in the drawings and described in detail above are illustrative only and it will be understood that some modifications and variations may be made in the structure and mode of operation thereof without departing from the scope of the invention defined by the following claims.

What is claimed is:

l. A dummy bar 12 for continuous casting apparatus which includes interchangeable beam blank and slab molds a and 10b of different sizes and a roller apron 13 for supporting and guiding four sides of a casting issuing from the mold and in which said roller apron is cross-sectionally adjustable to match different cross-sectional shapes and sizes of castings formed respectively by said molds, said dummy bar 12 comprising a chain of pivotally connected links 17 separably and pivotally attached to a dummy bar head 15, said dummy bar head being adapted for temporarily plugging the mold, each of said links having the cross-sectional shape of a beam blank and consisting of a web portion 23 extending between and connected to two parallel flange portions 22, each of said links 17 consisting of two halves separable at a break laterally across its web portion 23 with said halves being connected by at least one tie rod 26 and a spacer 28a or 28b adapted to be mounted between the halves of each link for adjusting the width of the links, said flange portion of each link having opposite edge surfaces 63 and outward end surfaces 35 and 36, and said web portion of each link having opposite side surfaces 23c, all of which surfaces are adapted to be engaged by said roller apron for supporting and guiding said chain of links.

2. The dummy bar of claim 1 in which said spacer 28b is adapted for adjusting the thickness of said web portion 23 of the link.

3. The dummy bar of claim 1 in which the spacers 28b are each thicker than the web portions 23 of the respective links for increasing the t thickness of each web portion therethrough at said opposite side surfaces engaged by said roller apron, and in which adjacent edges of said spacers in adjacent links in the chains are respectively concave and convex to match, said adjacent edges interfitting with clearance between.

4. The dummy bar of claim 1 in which the height of the flanges 22 of the links 17 are less than the corresponding dimension of the dummy bar head 15, and which includes at least one transition member 16 between the dummy bar head and a link at one end of said chain and pivotally connected thereto respectively, said transition member consisting of a web portion 23 between two flange portions, said web portion being centered relative to the height of said flange portions,

the flange portions of said transition member being the same height as the flange portions of the link at the end of the transition member which is adjacent to said link to which the transition member is connected, the height of the flange portions of the transition member increasing progressively to a greater height at the other end of the transition member adjacent to the dummy bar head, said greater height being substantially the same as the corresponding dimension of the dummy bar head.

5. The dummy bar of claim 4 in which each of said transition members 16 consists of two halves separable at a break laterally across its web portion 23 with said halves being connectable by at least one tie rod 26, and spacer 28a or 28b adapted to be mounted between the halves of each transition member for adjusting the width thereof.

6. The dummy bar of claim 5 in which said spacer 28b is adapted for adjusting the thickness of said web portion 23 of said transition member.

7. The dummy bar of claim 5 in which the spacers Zfib are each thicker than the web portion 23 of the respective transition members for increasing the thickness of each web portion therethrough at said opposite side surfaces engaged by said roller apron, and in which adjacent edges of said spacers in adjacent transition members and links in the chain are respectively concave and convex to match, said adjacent edges interfitting with clearance between.

8. The dummy bar of claim 5 in which the adjacent edges of the web portions 23 of adjacent transition members and links in the chain are respectively concave and convex to match, said adjacent edges interfitting with clearance between.

9. The dummy bar of claim 5 in which the adjacent end edges of the flange portions 22 of adjacent transition members 16 and links 117 overlap in offset relation to provide a substantially continuous planar guide surface along each opposite flanged side of the chain of transition members and links.

10. Continuous casting apparatus comprising a replaceable mold 10, a roller apron 13 for supporting nd guiding a casting issuing from the mold, said roller apron being cross-sectionally adjustable to match the cross-sectional shape and size of a casting from the mold, a chain of pivotally connected links 17 attached to a dummy bar head 15, said dummy bar head being adapted for temporarily plugging the mold; each of said links having the cross-sectional shape of a beam blank and consisting of a web portion 23 extending between and connected to two parallel flange portions 22, each of said links consisting of two halves separable at a break laterally across its web portion 23 with said halves being connectable by at least one releasable tie rod, spacer 28a or 28b adapted to be mounted respectively between the halves of each link for adjusting the width of the links thereby to adapt the chain of links to be supported and guided by said roller apron, means for moving the chain of links and dummy bar head from the roller apron onto a rack 71 for supporting the chain of links, two rows of cradle means 73 on said rack for receiving and supporting the flange portions of the links of a chain on the rack, said cradle means of at least one of said rows being movable on the rack away from and toward the other row for separating, and then moving together again, said halves of each link when the tie rods are released, said cradle means being adapted for supporting said flange portions so as to prevent the the respective link halves from tipping out of alignment with each other when the link halves are separated and moved together, whereby said links are separated and supported for insertion and removal of said spacers.

11. The continuous casting apparatus of claim 10 which includes means 76, 78 and 79 for simultaneously moving all the cradle means of one row relatively away from or toward all the cradle means of the other row. 

1. A dummy bar 12 for continuous casting apparatus which includes interchangeable beam blank and slab molds 10a and 10b of different sizes and a roller apron 13 for supporting and guiding fouR sides of a casting issuing from the mold and in which said roller apron is cross-sectionally adjustable to match different cross-sectional shapes and sizes of castings formed respectively by said molds, said dummy bar 12 comprising a chain of pivotally connected links 17 separably and pivotally attached to a dummy bar head 15, said dummy bar head being adapted for temporarily plugging the mold, each of said links having the cross-sectional shape of a beam blank and consisting of a web portion 23 extending between and connected to two parallel flange portions 22, each of said links 17 consisting of two halves separable at a break laterally across its web portion 23 with said halves being connected by at least one tie rod 26 and a spacer 28a or 28b adapted to be mounted between the halves of each link for adjusting the width of the links, said flange portion of each link having opposite edge surfaces 63 and outward end surfaces 35 and 36, and said web portion of each link having opposite side surfaces 23c, all of which surfaces are adapted to be engaged by said roller apron for supporting and guiding said chain of links.
 2. The dummy bar of claim 1 in which said spacer 28b is adapted for adjusting the thickness of said web portion 23 of the link.
 3. The dummy bar of claim 1 in which the spacers 28b are each thicker than the web portions 23 of the respective links for increasing the thickness of each web portion therethrough at said opposite side surfaces engaged by said roller apron, and in which adjacent edges of said spacers in adjacent links in the chain are respectively concave and convex to match, said adjacent edges interfitting with clearance between.
 4. The dummy bar of claim 1 in which the height of the flanges 22 of the links 17 are less than the corresponding dimension of the dummy bar head 15, and which includes at least one transition member 16 between the dummy bar head and a link at one end of said chain and pivotally connected thereto respectively, said transition member consisting of a web portion 23 between two flange portions, said web portion being centered relative to the height of said flange portions, the flange portions of said transition member being the same height as the flange portions of the link at the end of the transition member which is adjacent to said link to which the transition member is connected, the height of the flange portions of the transition member increasing progressively to a greater height at the other end of the transition member adjacent to the dummy bar head, said greater height being substantially the same as the corresponding dimension of the dummy bar head.
 5. The dummy bar of claim 4 in which each of said transition members 16 consists of two halves separable at a break laterally across its web portion 23 with said halves being connectable by at least one tie rod 26, and spacer 28a or 28b adapted to be mounted between the halves of each transition member for adjusting the width thereof.
 6. The dummy bar of claim 5 in which said spacer 28b is adapted for adjusting the thickness of said web portion 23 of said transition member.
 7. The dummy bar of claim 5 in which the spacers 28b are each thicker than the web portions 23 of the respective transition members for increasing the thickness of each web portion therethrough at said opposite side surfaces engaged by said roller apron, and in which adjacent edges of said spacers in adjacent transition members and links in the chain are respectively concave and convex to match, said adjacent edges interfitting with clearance between.
 8. The dummy bar of claim 5 in which the adjacent edges of the web portions 23 of adjacent transition members and links in the chain are respectively concave and convex to match, said adjacent edges interfitting with clearance between.
 9. The dummy bar of claim 5 in which the adjacent end edges of the flange portions 22 of adjacent transition members 16 and links 17 oVerlap in offset relation to provide a substantially continuous planar guide surface along each opposite flanged side of the chain of transition members and links.
 10. Continuous casting apparatus comprising a replaceable mold 10, a roller apron 13 for supporting and guiding a casting issuing from the mold, said roller apron being cross-sectionally adjustable to match the cross-sectional shape and size of a casting from the mold, a chain of pivotally connected links 17 attached to a dummy bar head 15, said dummy bar head being adapted for temporarily plugging the mold; each of said links having the cross-sectional shape of a beam blank and consisting of a web portion 23 extending between and connected to two parallel flange portions 22, each of said links consisting of two halves separable at a break laterally across its web portion 23 with said halves being connectable by at least one releasable tie rod, spacers 28a or 28b adapted to be mounted respectively between the halves of each link for adjusting the width of the links thereby to adapt the chain of links to be supported and guided by said roller apron, means for moving the chain of links and dummy bar head from the roller apron onto a rack 71 for supporting the chain of links, two rows of cradle means 73 on said rack for receiving and supporting the flange portions of the links of a chain on the rack, said cradle means of at least one of said rows being movable on the rack away from and toward the other row for separating, and then moving together again, said halves of each link when the tie rods are released, said cradle means being adapted for supporting said flange portions so as to prevent the respective link halves from tipping out of alignment with each other when the link halves are separated and moved together, whereby said links are separated and supported for insertion and removal of said spacers.
 11. The continuous casting apparatus of claim 10 which includes means 76, 78 and 79 for simultaneously moving all the cradle means of one row relatively away from or toward all the cradle means of the other row. 